Mr. Horner on the Geology of the Environs of Bonn. 451 



broken masses to which leaves are never attached, no decision can be pronounced as to the general 

 to which they belong more exact than that of resemblance. Faujas St. Fond, in a description of 

 a visit he made to the brown-coal mines at Lieblar, published in 1802, says that he obtained spe- 

 cimens of fruits found in the brown coal which Jussieu and other eminent botanists pronounced to 

 belong to the palm tribe*. The impressions of leaves are most distinct in the Papierkohle, the 

 sandstone and clay ironstone, and the leaves belonged, doubtless, to the stems which are associated 

 with them. 



In sinking a pit some years ago in the clay at Bruch near Ober Cassel, there was found a bed 

 of fragments of silicified wood four feet thick. Professor Noggerath made a very close exami- 

 nation of an extensive suite of specimens of the wood from this place, in the possession of Pro- 

 fessor Leonhard of Heidelberg, with Mr. C. Bernhard Cotta, the author of an excellent work 

 on fossil woods t. and the result was, that without a single exception they were all dicotyledonous. 

 There exist, however, in the museum of the University of Bonn, two specimens from this place of 

 a doubtful character. They are from three to four inches long, and about an inch and a half 

 thick, and are silicified. They were long imagined to be fir tops, but Professor Nees von Esen- 

 beck. Sen., who at the request of Professor Noggerath examined them with great care, was 

 of opinion that they are most probably portions of the root of a species of Fern \. Among the 

 specimens I obtained from this place is one in which the silicified woody fibres separate like some 

 kinds of glassy actinolite ; this variety is not uncommon ; some are found passing into the state of 

 semi-opal. At Alter Roth, near Haisterbach, I found in a friable sandstone a portion of a branch 

 of a tree, which is remarkable in this respect, that while the form of the branch with a knot in it 

 is perfectly preserved, the substance of the wood has been replaced, not as in the other instances 

 by silica in a state of minute division, but by a somewhat coarse quartzose sand. 



It does not appear that the vegetable remains contained in the brown-coal formation of this 

 district have as yet been described by any botanist of acknowledged authority. My friend Pro- 

 fessor Lindley has been so kind as to examine the specimens I have sent in illustration of this 

 paper, and the following communication from him contains the result of that examination. 



"The principal part of the impressions of leaves is in a state which renders it impossible to de- 

 " termine, with any certainty, the nature of the plants to which they have belonged. They consist 

 " generally of casts of portions of dicotyledonous foliage, of so common an appearance that no one 

 *' could have determined them with precision, even if they had been newly gathered and possessed 

 " of all those characters of texture, surface, colour, and odour, by which a botanist would be 

 " obliged, in the case of such fragments, to form his opinion. 



* " On trouve quelquefois dans les mines de terra d'Ombre de Liblar, des fruits qui ont au pre- 

 *' mier aspect la forme des noix ordinaires enveloppees de leur brou, mais en les examinant avec 

 " attentions Ton voit qu'ils en different totalement. Les botanistes les plus exerces, tels que de 

 " Jussieu, Desfontaines, Thouin, apres avoir examine et compare ces fruits ont trouve qu'ils avoient 

 '* un tres grand rapport avec les noix du palmier Areca. lis n'ont pas cru devoir affirmer que 

 ** ces fruits fussent directement ceux de I'Areca, mais ils ont une opinion unanime qu'ils ont ap- 

 " partenus a des arbres du genre palmier." — Annates du Museum d'Hist. Nat. i. 459. 



t Die Dendrolithen in Bezichung aufihren inneren Ban. Dresden, 1832. 4to. 



X M. Alex. Brongniart says, in treating of lignite, in 1823, " On n'y cite encore aucune fougere 

 " evidente, ni aucune des feuilles ou tiges des plantes de cette meme famille." — Diet, des Sciences 

 Naturelles, vol. xxvi. p. 360. 



VOL. IV. SECOND SERIES. 3 N 



